Orthogonal Frequency Division Multiple Access (OFDMA) technology is getting very popular in modern communication systems since the OFDMA technology can efficiently support multiple mobile stations with limited bandwidth and easily provide Quality of Service (QoS). The OFDMA technology is a multiple access version of orthogonal frequency-division multiplexing (OFDM). OFDM is a modulation technique for data transmission based on frequency-division multiplexing (FDM), which uses different frequency channels to transmit multiple streams of data. In OFDM systems, a wide channel is divided into multiple narrow-band sub-carriers, which allow orthogonal modulated streams of data to be transmitted in parallel on the sub-carriers.
In OFDMA systems, multiple subscribers can simultaneously use different sub-carriers for signal transmission. Thus, in an OFDMA system, multiple data bursts can be transmitted from a base station to multiple mobile stations in the same time frame but allocated in different frequency sub-carriers. Consequently, an OFDMA system can support multiple mobile stations using different sub-carriers.
In order to synchronize the transmitted data between the base station and the mobile stations, a local oscillator is used at each station to process the outgoing and incoming OFDMA signals. However, an OFDMA system is susceptible to frequency offset due to the oscillator mismatch between the base station and the mobile stations. Thus, it is necessary to determine the frequency offset and to compensate for the frequency offset when processing incoming and outgoing signals at each mobile station.
In view of this requirement, there is a need for an OFDMA device and method of correcting frequency offset in OFDMA signals.